Pagastia Oliver, 1959

Namayandeh, Armin, Hudson, Patrick L., Bogan, Daniel L. & Hudson, John P., 2024, Chironomidae (Diptera: Insecta) of Alaska, USA, with descriptions of new species and a checklist, Zootaxa 5511 (1), pp. 1-95 : 49

Pagastia Oliver, 1959

Oliver (1959) established the genus Pagastia to accommodate two species of Diamesinae that did not fit well in any known genus of the subfamily. The original descriptions of Pagastia partica and Pagastia artisia were from Roback (1957) under the genus Syndiamesa . Oliver (1959) found little differences between the two species, from the original description. Using some material collected from Cold Bay, Alaska, in August of 1952, he synonymized the two species, with Pagastia partica having priority. Additionally, Oliver (1959) described a new species, Pagastia orthogonia , from specimens collected during the same time from Cold Bay. Milner (1994) found P. othogonia as Pagastia sp. A in Wolf Point Creek of Glacier Bay National Park and Preserve. We found larvae of P. orthogonia to be quite common in Southwestern Alaska. In Southcoastal Alaska, we collected P. orthogonia in dozens of creeks, including Chester, South Fork Chester, North Fork Campbell, and Little Campbell Creeks in Anchorage; Crooked, Deep, Soldotna, and Twitter Creeks on the Kenai Peninsula; and Cottonwood, Deception, Troublesome, and Wasilla Creeks in the Mat-Su Valley.

We added new regional records of P. partica from the East Alsek River of Glacier Bay National Park and Preserve based on the adults collected in early September and from the Mendenhall River in late March. We found larvae of P. partica quite common in the lower braided portion of the East Alsek River. Tilley (1978) reported having found several larvae of Pagastia orientalis (Chernovskii, 1949) in the Atigun River of the Endicott Mountains in northern Alaska. This was later substantiated by Makarchenko & Makarchenko (2000), who also found larvae from Alaska, which were determined to be Pagastia orientalis (Chernovskii, 1949) . Webb et al. (2022) also confirm the presence of this species in Alaska with bar-coded larval specimens from the Charley River in the Yukon-Charley Rivers National Preserve.

Pagastia larvae have been reported from the Indian River basin on Baranof Island, Kuskokwin River, streams in the Kantishna Hills in Denali National Park, and the Koyukuk and Koktuli Rivers ( Arctos 2023). Larvae of this genus can be found in streams, rivers, reservoirs, lakes, and springs. The larvae are clingers associated with stone substrate and gut contents suggest they are both predators and collector gatherers ( Caldwell 2007).